Taking their first-ever silverware last year — the MLS Supporters’ Shield for the best record in the MLS — earned the Red Bulls a chance to win a second trophy, giving them a berth in the CONCACAF Champions League. And they opened the competition in dominant fashion, taking a must-win game against El Salvador’s CD FAS 2-0 Tuesday night.

“We said: ‘Have a bit of pride in the performance,’ ” Tim Cahill said. “It was trying to make a statement, continue to win games.

“I think people were waiting for us to slip up, not put a strong performance out. But I felt we put on a good showing.’’

FAS lost its earlier Group 3 matches to Montreal, leaving the Red Bulls six points behind the MLS rival Impact before they even kicked off. The Red Bulls had no room for error and made none, getting goals from newcomer Saer Sene and Lloyd Sam and a rare clean sheet from backup goalkeeper Ryan Meara and their maligned defense.

“MLS matches are a lot more physical than what we played [Tuesday],’’ said Sam, who scored in the 70th minute. “Look at the table: One has six already, so a win was a must.’’

It was the Red Bulls’ first Champions League appearance since 2009 — which was earned by their appearance in the 2008 MLS Cup — and first-ever win in the competition. Sene — acquired Aug. 12 from New England — opened the scoring in the 11th minute after Cahill headed down Ambroise Oyongo’s cross.

“I’m just excited to be on the field,” Sene said. “It doesn’t matter if its CONCACAF or an MLS game, I’m just happy to be on the field and that the coach gives me a chance to enjoy football again.’’

Sene worked well up top with Cahill, with Thierry Henry and Bradley Wright-Phillips getting a night off.

Coach Mike Petke gave a debut to centerback Damien Perrinelle and played backups Meara, Armando and Richard Eckersley, with the Red Bulls using Sam and Oyongo to mercilessly attack FAS’ 3-5-2 down the wings.

“I’m very happy to be in this competition,’’ Petke said. “I think it’s a phenomenal platform for MLS, for us, and I’m looking forward to going down to FAS to be honest with you and experience something like that.’’

CONCACAF is the federation for North and Central America and the Caribbean. The Red Bulls return to MLS action Sunday at archrival and East-leading DC, and play their next Champions League match Sept. 17 at Montreal.